1. Field of the Invention
The present invention relates to a computer room reduced air flow method and apparatus but is not limited to use in computer rooms and instead can be utilized with respect to any equipment assembly requiring cooling which is positioned in a room. The method and apparatus described below permits achieving energy savings while reducing the amount of air required to cool electronic/heat generating equipment, wherein a computer rack heat extraction device (CRHED) or similar device is utilized. The method and apparatus permits the collection of heat generating, for example, by the rack electronic equipment.
2. Discussion of the Background
A conventional computer room method and assembly is illustrated in FIG. 3 which exemplifies the approach for cooling electronic equipment commonly used currently wherein an array of racks of equipment are positioned on a raised floor. FIG. 3 illustrates an air-conditioning system used in the method and apparatus of a conventional system wherein a room space 1 defined by a room floor 2, side walls 3 and a ceiling 4 having a plurality of ceiling panels 4a is provided. The room floor 2 is positioned a predetermined distance above a base floor 5 such that the room floor 2 and the base floor 5 in combination form a double floor structure having a free space 6 (i.e., an air passageway) formed therein. A rack 7 for one or more computer processing units (CPUs) is disposed on the floor 2 wherein electronic cables for the rack are capable of being housed in the free space 6 of the double floor structure but can be specifically communicated to the rack separate from the free air space, if desired.
In installing each of the CPUs or other equipment on the rack of the floor, a plurality of support members 2b can be provided which are stationary by being fixed by bolts or similar fastening elements to predetermined positions on the floor 2.
The rack 7 is positioned in a casing 8 having air inlets 8a and air outlets 8b formed respectively in a bottom plate of a casing 8 and in the ceiling portion of the casing 8. A computer case fan 9 is operable during operation of the equipment 7 so as to assist the air flow upwardly from the casing through the air outlets 8b. As shown in FIG. 3, the CPU members are arranged in an air passageway formed within the casing 8. The floor 2 includes a plurality of floor panels located on support members or pedestals 2b, one panel 2a of which includes a plurality of perforations to allow air flow as indicated by the arrows to flow through the front of the outside housing to casing 8, through the CPU rack 7 and out the back of casing 8. A cooling unit 14 is positionable either inside or outside the room 1 and is communicated with a heat exchanger or other air conditioning equipment so as to permit a cooling coil 15 located within unit 14 to cool air blowing there through. The cooling unit 14 also includes a fan 16 which is positionable below cooling coil 15. An inlet 20 is provided to allow air from the room to flow thereinto from the room, the air in the casing 8 mixing with room air prior to being introduced into the cooling unit 14, as illustrated in FIG. 3. The fan 16 is therefore arranged between the air inlet 20 and an air outlet 22 located at the lower portion of unit 14 and feeds air into the free space 6 located above the base floor. The fan 16 thus permits air in the interior of the room to be sucked into the air inlet 20 of the casing 8 and also permits the air in the room to pass through cooling coil 15. The air in the room is typically at a temperature of 75xc2x0 F.xc2x1.
The above-noted approach for cooling electronic equipment thus permits the area in the free space 6 below the raised floor 2 to be used for cable management and also serves as a supply air plenum. The computer room air conditioning units (CRACUs) utilize cooling coil 15 to cool the air. The CRACUs supply conditioned air at approximately 55xc2x0 F. to the underfloor supply air plenum or free space 6. The floor tiles with perforations or slots to allow air to flow from under the raised floor to above the floor are positionable below or are located adjacent to the rack 7. Other perforated tiles are positionable throughout the room to provide air supply to other heat generating equipment and to maintain the room at an ambient environment.
As illustrated by the arrows in FIG. 3 showing the air flow, the conditioned air is then drawn into the rack 7 by either convection by air flow from perforated panels 2a and/or opening 8a to the casing 8 or by fans 9 located in the top of the racks. The air enters the racks at a temperature of approximately 55xc2x0 F., is heated by the CPUs or other electronic equipment, and flows upwardly out of the rack at approximately a temperature of 95xc2x0 F. The warm air leaves the rack and mixes with the conditioned ambient environment of the room 1 which is at a temperature of approximately 75xc2x0 F., and thus returns to the CRACUs at a temperature of approximately 75xc2x0 F. as illustrated in FIG. 3.
Before the foregoing, it can be understood that a conventional CRACUs have a 20xc2x0 delta T (xc2x14xc2x0 F.) across the cooling coil 15. This is also coincident with the space delta T which is defined as being the difference in temperature between the air supplied to the space and the air returned from such space. The temperature of the air returned from the space is usually coincident with the ambient space temperature such that the return air at 75xc2x0 F. enters the return on top of the CRACUs, passes along the cooling coil 15 and is discharged at a temperature of substantially 55xc2x0 F. at the bottom of unit 14 so as to pass into the free space 6. The required air quantity to cool such space is a direct function of the space delta T. The equation set forth below is used to calculate the required air flow or cubic feet per minute (CFM) of air to cool a space:
CFM=BTUH/1.08xc3x97delta T 
From the foregoing, it can be appreciated that the disadvantage of the conventional system set forth above requires a significant amount of fan horsepower for operation and thus the need has arisen for reducing the amount of horsepower necessary to operate the fan 16.
Devices of the type described above are exemplified, for example, by U.S. Pat. No. 5,718,628; U.S. Pat. No. 4,774,631 and U.S. Pat. No. 5,910,045, the disclosure of each of which is herein incorporated by reference, as is the disclosure of parent application Ser. No. 09/784,238, the priority of which has been claimed in the present application.
The original concept by the inventors of the present application is exemplified by FIG. 4 of the present application. Such figure shows an air conditioning system used in a method and apparatus as described in such application. As shown therein, the room space is defined by room floor 2, sidewalls 3 and an upper ceiling 4 wherein a lower ceiling 4a is formed, for example, of ceiling tiles defining, a ceiling plenum 4b, and a base floor 5. The room floor 2 is formed a predetermined distance from the base floor such that the room floor 2 and the base floor 5 collectively form a double floor structure having a free space 6 or air passageway formed therein within which electric cables may also be housed. As shown in FIG. 4, air flow from space 6 can enter one side portion of each of the CPU racks and flow across the same towards a plenum 8c which can run the full length of the equipment assembly so as to permit air to flow across each CPU in the rack and then flow upwardly towards a plurality of ducts 24. The ducts 24 are sealed with respect to the equipment assembly by, for example, rubber gaskets wherein similar rubber gaskets 26 are provided between the duct 24 and the lower ceiling 4a. Also provided are computer case fans 24b and 24c, if desired, to assist in air flow through the ducts 24.
FIG. 1 shows an air conditioning system use in the method and apparatus according to an additional earlier concept also developed by the inventors. As shown therein, the structure corresponding to that described above with regard to FIG. 3 utilizes the same reference numbers. In this regard, it is noted that the embodiment shown in FIG. 2 utilizes an attachment either on the back or top of the computer rack (or cabinet) to collect the warm air from the equipment in the rack. The apparatus as shown in FIG. 1, to the contrary, uses space available within the back and top of the rack for the same purpose wherein the use of the existing space allows for both space and cost efficiencies. The apparatus shown therein utilizes a cavity type front door 8 consisting of a solid outer panel 8f and a perforated plate inner panel 8b. Cooling air from below the raised floor 2 is directed first into an air plenum in the bottom of the rack. From the plenum, the cooling air is directed into the air space or cavity 8d and the door that extends the entire front of the rack 7. The air cavity channels the cool air and distributes the cool air more evenly across the front of the equipment in the rack 7. Therefore, this improvement in the distribution of air allows for more even cooling of the equipment.
The design shown in FIG. 1 also incorporates an air space or cavity 8e between the perforated plate 8b and the front 7a of the equipment 7. This air space 8e allows for some re-circulated air to pass from the back 7b of the rack (i.e., the warm side) to the front 7a of the rack 7 (the cold side). Some recirculation may be required since the internal fans (not shown) in the equipment in the rack 7 may be moving more air than is supplied to the rack from the under-floor system described above. The above-noted design allows for either a single fan or a plurality of fans 25 at the top of the rack to exhaust the heat. The fan or fans 25 may be a single speed, variable speed or adjustable speed type of fan, depending upon the specific need for the device. FIG. 2 illustrates the manner in which perforated panel and the solid panels 8a and 8c at the front and back of the cabinet are pivotable so as to be opened for repair and/or replacement of the equipment in the rack 7. The flow arrow shown in FIG. 5 serves to illustrate the manner in which air flow occurs, including exiting of air into the ceiling plenum 4b. 
An object of the present invention is to provide a method and apparatus which utilizes an increased delta T to reduce the required air quantity, thus resulting in a reduced airflow method and apparatus. Specifically, the present invention utilizes an approximately 40xc2x0 F. delta T to reduce the CFM by substantially 50%. The substantially 50% reduction in the airflow will serve to effectively correspondingly reduce the required power by substantially 50%, resulting in substantial energy savings. A key element of the method and apparatus is an increase in delta T above what is conventionally used. The present invention is capable of operating in a range of delta T from 25xc2x0 F. to 45xc2x0 F. In this regard, it is noted that the use of a 40xc2x0 F. in the description set forth below is solely exemplary in illustrating the device and greater or lesser temperature variations are possible.
An object of at least one embodiment of the present invention is to provide an air conditioning method and apparatus which utilizes the steps of supplying cooling air generated from a cooling apparatus into an air passageway formed below a floor; guiding the cooling air within the air passageway into an equipment assembly disposed on the floor through an opening located in the floor; communicating the cooling air introduced into the equipment assembly into a plenum and introducing the air released from within the equipment into the plenum for communicating such released air to the cooling apparatus. The method may also include the step of guiding the air from the equipment assembly through at least one duct into the plenum and may include the step of cooling the cooling air generated from the cooling apparatus to a temperature of substantially 55xc2x0 F. while also heating the air released from the equipment assembly to a temperature of substantially 95xc2x0 F. prior to introducing such air to the cooling apparatus so as to form a closed loop in terms of cycling of the air through the cooling assembly and the equipment assembly.
A further object of the present invention is to obtain a temperature differential between the air supplied to the air passageway or plenum from the cooling apparatus and the air introduced into the plenum from the equipment assembly so as to be substantially 40xc2x0 F., thus permitting lower power requirements of the fan utilized to assist flow of the air in the closed loop.
A further object of the present invention is to position the fan between the cooling apparatus and the air passageway so as to permit blowing of the air into the passageway towards the equipment assembly, although it is understood that the fan can be located anywhere within the closed loop so as to assist flow of air between the blowing apparatus and the equipment assembly.
A further object of the present invention is to provide a method and apparatus wherein the cooling assembly is located either within or outside the computer room, the equipment assembly comprising either at least one computer processing unit or other type of processing unit in combination with an additional heat generating equipment or without such equipment. In addition, a further object, of the present invention is to cool equipment assembly generating heat which does or does not include computer equipment.
An additional object of the present invention is to provide an air conditioning assembly for performing the method described above.
An additional object of the present invention is to provide a CPU rack housing with a cavity type front door having a substantially solid outer panel and a perforated plate inner panel so that cooling air from below the raised floor is directed first into an air plenum in the bottom of the rack. From the plenum, the cooling air can be directed into an air space or cavity in the door that extends the entire front of the rack such that the air cavity channels cool air and distributes the cool air more evenly across the front of the equipment in the rack and thus allows for more even cooling of the equipment.
A further object of the present invention is to provide an improved design which incorporates an air space or cavity between the perforated plate and the front of the equipment so that the air space allows for some re-circulated air to pass from the back of the rack (the warm side) to the front of the rack (the cold side).
An additional object of the present invention is to permit either a single fan or a plurality of fans to be positioned at the top of the rack so as to exhaust the heat wherein the fan or fans have a single speed, variable speed or adjustable speed capability, depending upon the specific need for the device.
Another feature of the device is the ability to cool more heat generating electronic equipment in a cabinet than can be cooled with the conventional system. The conventional system as shown in FIG. 3 has been shown to experience overheating of equipment at conditions above 4 KW of name plated heat rejection of electronic equipment per cabinet. A cabinet equipped with the CRHED and associated improvements will effectively cool up to 8 KW of name plated heat rejection of electronic equipment. The ability to cool more equipment in a single cabinet result in more revenue per unit area of a building.
Yet an additional feature of the present invention is to provide a heating and cooling method in accordance with the above-noted objects wherein cooling air is fed to the heat generating electronic equipment in the cabinet by means of a cooling duct in the ceiling which permits air to be fed to the equipment at a temperature of substantially 55xc2x0 F. which is thermally isolated from the remaining volume of the ceiling plenum itself which permits return of air via a duct from the heating equipment at a temperature of substantially 95xc2x0 and which is returned to the heating and air conditioning system described above. This permits the cooling air to be fed to the equipment via the ceiling rather than via than the plenum provided beneath the floor and above the base floor.
It is yet an additional object of the present invention to provide a method and apparatus described in the foregoing paragraph but wherein the air upon being heated is returned via one or more fans from the electronic equipment and the heat is released into the room for return to the heating and air conditioning assembly. This embodiment permits the cooled air plenum provided in the ceiling duct to communicate cooled air at a temperature of substantially 55xc2x0 F. into the equipment via a duct which permits heated air from the heat generating electronic equipment to exit from the cabinet of the equipment into the ceiling for return to the heating and air conditioning system for being cooled to a temperature of substantially 55xc2x0 by the cooling unit 14 so as to complete the cycle of flow of air to and from the heat generating electronic equipment in the cabinet.